我們利用飛秒激發-探測光游離-光裂解(Femtosecond Pump-Probe Photoionization-Photofragmentation)光譜術結合質譜偵測技術研究N,N-dimethyl-3-phenpropylamine (DMPPA), N-methylphenyl-3-propylamine (MPPA) 及3-phenylpropylamine (PPA)陽離子的電荷轉移反應及離子基態構型緩解動力學，並比較與實驗室前人對2-phenylethyl-N,N-dimethylamine (PENNA)、N-methyl-2-phenylethylamine (MPEA)與2-phenylethylamine (PPA)之實驗結果有何異同。我們利用1+1 共振多光子游離(Resonance Multiphoton Ionization, REMPI)技術使處於基態(S0)之分子吸收兩個波長為266.1 nm的激發雷射光子，先到達S1 state後再被游離，接著導入波長為798.3 nm的探測雷射將其激發至更高的離子激發態後碎裂。透過調整探測脈衝與激發脈衝間的延遲時間並擷取離子訊號，我們可以得到離子瞬時光譜。我們使用連續反應動力學模型適解所得到的離子瞬時光譜。DMPPA+ 與PPA+的損耗瞬時光譜皆得到三個時間常數，而MPPA+的瞬時光譜則得到兩個。我們同時也量測苯丙醇(3-phenyl-1-propanol, PPAL+)的離子損耗瞬時光譜並進行適解，由於PPAL+不會進行電子轉移，故將PPAL+適解出的時間常數與DMPPA+、MPPA+和PPA+之時間常數比較，即可判斷屬於電子轉移的時間常數。由於次皮秒等級的時間常數在PPAL+之瞬時光譜未被觀察到，而只出現在DMPPA+、MPPA+和PPA+之瞬時光譜，故我們認為此次皮秒時間常數屬於電子轉移，DMPPA+、MPPA+及PPA+這些陽離子內的電子轉移過程分別約為0.18、0.24及0.17 ps，而之後數皮秒至十幾皮秒的過程在PPAL+的瞬時光譜中亦有出現，因此可歸為自陽離子之弗蘭克-康登(Franck-Condon)構型緩解至陽離子基態(D0)穩定結構之過程。

We studied the ultrafast charge transfer and conformational relaxation dynamics of N,N-dimethyl-3-phenpropylamine (DMPPA), N-methylphenyl-3-propylamine (MPPA) and 3-phenylpropylamine (PPA) cations by utilizing femtosecond pump-probe photoionization-photofragmentation spectrometry along with time-of-flight mass spectrometry. We also compared the results with those of 2-phenylethyl-N,N-dimethylamine (PENNA), N-methyl-2-phenylethylamine (MPEA) and 2-phenylethylamine (PPA). Neutral DMPPA, MPPA and PPA seeded in a helium free jet are photoionized by femtosecond 1+1 resonance-enhanced multiphoton ionization via their S1 state, and the subsequent dynamics occurring in the cations is probed by delayed pulses that result in ion fragmentation. With a sequential first-order kinetic model, three time constants are obtained from the depletion transients of DMPPA+ and PPA+, respectively, while for MPPA+ we only found two time constants. Comparing the results with that of 3-phenyl-1-propanol (PPAL+), which does not undergo charge transfer, we assigned the sub-picosecond time constants of DMPPA+ (0.18 ps), MPPA+ (0.24 ps) and PPA+ (0.17 ps) to the charge transfer dynamics, and the rest are assigned to conformational relaxation dynamics, where the cations go from their Franck-Condon structures to the cation ground state(D0) stable conformation after charge transfer.

1. A. Shah, B. Adhikari, S. Martic, A. Munir, S. Shahzad, K. Ahmad, and H.-B. Kraatz, Chem. Soc. Rev. 44, 1015 (2015)
2. E. W. Schlag, S. Y. Sheu, D. Y. Yang, H. L. Selzle, and S. H. Lin, Angew. Chem. 46, 3196 (2007)
3. E. W. Schlag, S. Y. Sheu, D. Y. Yang, H. L. Selzle, and S. H. Lin, Proc. Natl. Acad. Sci. U.S.A. 97, 1068 (2000)
4. S. S. Isied, M. Y. Ogawa, and J. F. Wishart, Chemical Reviews 92, 381 (1992)
5. M. R. Wasielewski, Chem. Rev. 92, 435 (1992)
6. M. Gilbert and B. Albinsson, Chem. Soc. Rev. 44, 845 (2015)
7. F. D. Lewis, R. L. Letsinger, and M. R. Wasielewski, Acc. Chem. Res. 34, 159 (2001)
8. D. M. Adams, L. Brus, C. E. D. Chidsey, S. Creager, C. Creutz, C. R. Kagan, P. V. Kamat, M. Lieberman, S. Lindsay, R. A. Marcus, R. M. Metzger, M. E. Michel-Beyerle, J. R. Miller, M. D. Newton, D. R. Rolison, O. Sankey, K. S. Schanze, J. Yardley, and X. Y. Zhu, J. Phys. Chem. B 107, 6668 (2003)
9. W. B. Davis, W. A. Svec, M. A. Ratner, and M. R. Wasielewski, Nature 396, 60 (1998)
10. P. F. Barbara, T. J. Meyer, and M. A. Ratner, J. Phys. Chem. 100, 13148 (1996)
11. J. Jiang, A. Alsam, S. Wang, S. M. Aly, Z. Pan, O. F. Mohammed, and K. S. Schanze, J. Phys. Chem. A 121, 4891 (2017)
12. Y. Shibano, H. Imahori, P. Sreearunothai, A. R. Cook, and J. R. Miller, J. Phys. Chem. Lett. 1, 1492 (2010)
13. J. Jortner, M. Bixon, H. Heitele, and M. E. Michelbeyerle, Chem. Phys. Lett. 197, 131 (1992)
14. J. Jortner, M. Bixon, B. Wegewijs, J. W. Verhoeven, and R. P. H. Rettschnick, Chem. Phys. Lett. 205, 451 (1993)
15. R. Weinkauf, P. Schanen, D. Yang, S. Sonkara, and E. W. Schlag, J. Phys. Chem. 99, 11255 (1995)
16. R. Weinkauf, P. Schanen, A. Metsala, E. W. Schlag, M. Burgle, and H. Kessler, J. Phys. Chem. 100, 18567 (1996)
17. L. Lehr, T. Horneff, R. Weinkauf and E. W. Schlag, J. Phys. Chem. A, 109, 8074 (2005)
18. W. Cheng, N. Kuthirummal, J. L. Gosselin, T. I. Solling, R. Weinkauf, and P. M. Weber, J. Phys. Chem. A 109, 1920 (2005)
19. R. Weinkauf, L. Lehr, and A. Metsala, J. Phys. Chem. A 107, 2787 (2003)

20. 周威銧, 胞嘧啶之氣相超快激發態動態學研究：激發態衰減時間與激發能量的依存性,in 化學系. 2008, 國立清華大學: 新竹市. p. 106.
21. 蔡宗廷, 超快光游離誘發酚-氨錯合物陽離子內之質子轉移動態學研究,in 化學系. 2015, 國立清華大學: 新竹市. p. 106.
22. 陳依微, 酚-氨陽離子錯合物中之超快質子轉移反應動態學研究,in 化學系. 2011, 國立清華大學: 新竹市. p. 91.
23. 何智偉, 氣相飛秒化學反應動態學研究1.二甲基亞碸之超快三體光解反應動態學2.偶氮苯陽離子在異構化途徑之同調振動,in 化學系. 2008, 國立清華大學: 新竹市. p. 226.
24. Eldredge, B.A.A.P., General Chemistry: Principles, Patterns, and Applications, v. 1.0 (2 Volume Set).
25. Smalley, R.E., L. Wharton, and D.H. Levy, Acc. Chem. Res. 10, 139 (1977)
26. Wiley, W.C. and I.H. McLaren, Rev. Sci. Instrum. 26, 1150 (1955)
27. M. Takahashi and K. Kimura, J. Chem. Phys., 97, 2920 (1992)
28. R.D. Bowen and A. Maccoll, Org. Mass Spectrom, 19, 379 (1984)
29. E.K. Chess, R.L. Lapp and M.L. Gross, Org. Mass Spectrom., 17, 475 (1982)
30. 鄭博元教授, Conference in Memory of the Nobel Laureate Ahmed Zewail 演講之投影片(2018)
31. 楊博竣, 超快光游離誘發2-苯基乙基-N,N-二甲基胺陽離子內之電荷轉移動態學研究,in 化學系. 2018, 國立清華大學: 新竹市.